Typically, tape guides are needed to control the lateral movement of magnetic tape as it is moved longitudinally along a tape path. A tape path for a magnetic tape extends longitudinally between tape reels and across a magnetic tape head which is configured to read and/or write magnetic signals with respect to the magnetic tape.
The magnetic tape may be laterally misaligned with respect to the magnetic tape head as it is fed from a tape reel, and a function of a tape guide is to bring the magnetic tape into alignment. The variation of the magnetic tape in the lateral or transverse direction may be considered the angle of attack from the supply reel with respect to the tape guide.
Tape guides may have flanges at either side of the magnetic tape to provide a force against the side of a misaligned magnetic tape, the force tending to align the magnetic tape. In one example, the flanges may be stationary flanges, in which case the magnetic tape slides along the flanges, the edges potentially cutting into the flanges at the maximum angle of attack of the magnetic tape, and potentially frictionally and mechanically damaging the magnetic tape.
Tape guides may alternatively comprise roller guides in which the rolling action of the tape guide about its rotational axis tends to center the magnetic tape, and may have annular flat flanges that are perpendicular to the axis of rotation. The fact that the magnetic tape entering the tape guide may be axially misaligned creates the opportunity for an edge of the magnetic tape to be forced against one of the flanges, and potentially to impact the shoulder at the top or leading edge of the flange. This may result in a mechanical “working” of the edge of the magnetic tape which may result in the edge becoming buckled or “rolled”. Further, the tape edge to roller guide condition may fatigue the tape edge and result in permanent deformation of the magnetic tape, cracking and de-lamination of the magnetic coating of the tape/media structure, and/or the generation and deposition of media products “debris” onto the tape guide flange. Debris contamination on the flange has the potential to introduce a transient lateral motion to the magnetic tape as the magnetic tape edge contacts the contaminant. The transient lateral motion may be sufficiently great that the track following capability of the tape servo system of the magnetic tape head of the tape drive is exceeded.